The present invention generally relates to the field of providing alternator pole piece claw assemblies and more specifically to the providing of magnetic material star shaped blanks which may be formed into claw shaped alternator pole piece rotor assemblies.
There are many known techniques for the manufacture of alternator pole piece rotor claw assemblies. These claw assemblies are metallic, magnetic material assemblies substantially comprising a plurality of extending finger projections which extend from a substantially planar base plate having a through hole therein for through passage of the alternator rotating shaft. The rotor claw assembly is fixed to the alternator shaft for integral rotation therewith. The extending magnetic fingers of the claw assembly are intended for interdigitation with similar opposing claw pole fingers to form the standard interdigitated rotor claw pole configuration in common use today.
One prior technique of manufacturing such claw pole assemblies is to begin with a cylindrical slug of magnetic material which is then subjected to extreme pressures in order to extrude the material into the desired claw configuration. This type of process requires extremely expensive production equipment and subjects the magnetic material to extreme forming pressures.
Another prior method of forming the desired alternator claw pole piece configuration comprises stamping star shaped blanks from flat plate sheet stock of magnetic material. The star shaped, preferably a six point star, blanks are then cold formed by a press such that a center through hole is formed in the main claw planar body while the extending star fingers are bent to form projecting arms which project in the same direction away from the substantially planar main body of the claw pole piece. While this process minimizes the expenditure necessary for the required claw pole piece manufacturing equipment and also minimizes the pressures which must be applied to the magnetic material during the manufacture of the claw pole piece, the stamping out of the star shaped blanks from the magnetic material flat plate stock results in typically a more than 40% loss of the magnetic material plate stock. This loss of magnetic material results in an increase in the material cost for the resultant alternator claw pole piece.